EP0524376A1

EP0524376A1 - Apparatus for dissolution of gas in liquid

Info

Publication number: EP0524376A1
Application number: EP92106451A
Authority: EP
Inventors: Gene E. Mazewski
Original assignee: Envirex Inc
Current assignee: Siemens Water Technologies Holding Corp
Priority date: 1991-07-10
Filing date: 1992-04-14
Publication date: 1993-01-27
Also published as: CA2056760A1; MX9102495A; JPH06142681A; CN1068276A; AU8709491A

Abstract

An apparatus for dissolving gas in a downflow of liquid, the apparatus comprising an outer vessel (14) including an upper end having an inlet (20), and a lower end having an outlet (24), the outer vessel defining a flow chamber for conducting the downflow between the inlet and the outlet, a funnel member (38) including a tubular portion which defines at least part of the inlet, and which cooperates with the outer vessel to define a collection well, and a downwardly diverging portion extending downwardly into the flow chamber from the tubular portion, the downwardly diverging portion including an outlet end, and defining a bubble contact chamber, and a mechanism (52) for introducing bubbles of gas into the downflow, the mechanism for introducing including a source of gas under pressure, and a bubble dispersing device (60) connected to the source, and positioned within the flow chamber adjacent the outlet end of the downwardly diverging portion so that the bubbles travel in a countercurrent direction into the bubble contact chamber and toward the inlet, and wherein the bubbles are sized to have a buoyant velocity greater than the downflow velocity of the liquid exiting the outlet end, and wherein the downflow velocity of the liquid in the tubular portion is greater than the buoyant velocity of the bubbles.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to the dissolution of gas in a liquid, and more particularly to an apparatus for dissolving gas in a liquid downflow.

Reference to Prior Art

In many processes it is desirable to dissolve gases in liquids. Such processes include the dissolution of oxygen in water in waste water treatment and other water treatment technologies.
In U.S. Patent No. 3,643,403, issued February 22, 1972 to Speece, a downflow bubble contact aeration apparatus includes a bubble disperser mounted within a downwardly diverging funnel. Bubbles emitted by the disperser are restricted to downward movement in the direction of water flow for cocurrent contact with the water.
In U.S. Patent No. 4,466,928, issued August 21, 1984 to Kos, an apparatus for dissolution of gases in liquid is disclosed. In Kos, gas is introduced into a contact chamber or into the liquid stream above the contact chamber for cocurrent contact with the liquid. It is important in Kos that the downflow velocity of the liquid in the contact chamber be greater than the rising velocity of the gas bubbles so that a continuous downward flow of bubbles is accomplished.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for dissolving gas in a liquid, the apparatus utilizing countercurrent contact of gas bubbles with the liquid for efficient gas dissolution, and introduction of the bubbles into the apparatus in the area adjacent the outlet so that liquid leaving the apparatus is contacted with high quality gas.
An object of the present invention is the provision of a gas dissolution apparatus which functions to efficiently and economically dissolve gas in a liquid, and which is easy to operate and maintain.
Another object of the present invention is the provision of an improved gas dissolution apparatus which introduces gas bubbles into a downflow of liquid for countercurrent contact of bubbles with the liquid.
Another object of the present invention is the provision of an improved gas dissolution apparatus which includes a flow confinement member having an inlet and an outlet, and means for introducing bubbles into the liquid flowing between the inlet and the outlet in the area adjacent the outlet so that the liquid leaving the flow confinement member is contacted by the bubbles shortly after they are introduced.
Another object of the present invention is the provision of a gas dissolution apparatus which includes a flow confinement member comprising an outer vessel having an inlet and an outlet, and a funnel member including a downwardly diverging portion extending into the outer vessel and communicating with the inlet for delivering a flow of liquid into the outer vessel.
Another object of the present invention is the provision of a liquid treatment system which incorporates the aforementioned gas dissolution apparatus, and which functions to remove contaminents from the liquid. In one embodiment of the invention the liquid treatment system can be used to purify groundwater by removing fuel constitutents therefrom.
The gas dissolution apparatus comprises a flow confinement member which includes an outer vessel defining a flow chamber for conducting liquid between an inlet and an outlet, and a funnel member extending downwardly into the flow chamber from the inlet for conducting a downflow of liquid into the flow chamber. The funnel member includes a downwardly diverging portion which has a lower outlet end, and which defines a contact chamber.
The gas dissolution apparatus also comprises means for introducing bubbles of gas into the liquid downflow. The introducing means includes a bubble dispersing device positioned adjacent the lower or outlet end of the funnel member so that gas bubbles emitted by the bubble dispersing device travel upwardly into the contact chamber for countercurrent contact with the liquid. The bubble dispersing device is preferably positioned within the flow chamber in the area adjacent the outlet of the outer vessel so that liquid leaving the gas dissolution apparatus is contacted with gas bubbles shortly after their emission from the bubble dispersing device. This arrangement is intended to achieve greater dissolution of gas in the liquid.
In alternative embodiments of the invention, the flow confinement member can include only the outer vessel or the funnel member, with the bubble dispersing device being positioned to accomplish countercurrent contact of the bubbles with the liquid. In either alternative embodiment, the bubble dispersing device is preferably positioned in proximity to the outlet.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed descriptions, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side view, partially in section, of a gas dissolution apparatus embodying the invention.
Figure 2 is a view taken along line 2-2 in Figure 1.
Figure 3 is a view taken along line 3-3 in Figure 2.
Figure 4 is a schematic diagram of a liquid treatment system which utilizes the gas dissolution apparatus shown in Figure 1.
Figure 5 is a side view, partially in section, of an alternative embodiment of the gas dissolution apparatus shown in Figure 1.
Figure 6 is a side view, partially in section, of a second alternative embodiment of the gas dissolution apparatus shown in Figure 1.
Figure 7 is a side view, partially in section, of a third alternative embodiment of the gas dissolution apparatus shown in Figure 1.
Figure 8 is a side view, partially in section, of the reactor shown in Figure 4.
Before one embodiment of the invention is explained in detail it is to be understood that the invention is not limited in its application to the details of the construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

GENERAL DESCRIPTION

Figure 1 illustrates a gas dissolution apparatus 10 which functions to dissolve gas in a liquid, and which embodies various features of the invention. While the gas dissolution apparatus 10 can be used to dissolve a variety of different gases in different liquids, in the illustrated arrangement the apparatus 10 dissolve oxygen in water.
The gas dissolution apparatus 10 includes a flow confinement member 12 comprising an annular outer tank or vessel 14 which is preferably a pressure vessel rated to withstand pressure of at least 30 psi. The outer vessel 14 is supported on legs 16 and includes an upper end 18 having an inlet 20, and a lower end 22 having an outlet 24 which is defined by an outlet conduit or pipe 26. A cylindrical flow chamber 30 is defined by the outer vessel 14 and conducts water between the inlet 20 and the outlet 24.
As shown in Figure 2, the outer vessel 14 also includes one or more gas feed pipes 32 (two are shown) which protrude through the lower end 22. Each feed pipe 32 has an outside end which is connectable to a pressurized gas source 34 (see Fig. 4). In the illustrated arrangement the source 34 supplies air, oxygen enriched air, or commercial oxygen to the gas dissolution apparatus 10.
The outer vessel 14 is also provided with a manway pipe 36 which projects outwardly from the lower end 22 of the outer vessel 14, and which provides access to the flow chamber 30 to clean or maintain the gas dissolution apparatus 10. A removeable cover 37 is secured to the manway pipe 36 via fasteners or other means.
The flow confinement member 12 also comprises a funnel member 38 which extends downwardly into the flow chamber 30 from the upper end 18 of the outer vessel 14. As shown in Figure 1, the funnel member 38 includes a tubular inlet portion 40 which extends through the upper end 18, and which defines the inlet 20. The inlet portion 40 cooperates with the outer vessel 14 to define a collection well 42 in the uppermost part of the flow chamber 30. The collection well 42 has a small volume so that only small quantities of gas can collect therein. If the gas collecting in the collection well 42 includes volatile fumes, the amount of these fumes which collect is limited by the size of the collection well 42, so that the risk and severity of fire or explosion is reduced.
The funnel member 38 also includes a frusto-conical, downwardly diverging portion 44 which extends into the flow chamber 30 from the inlet portion 40, and which has an increasing flow area in the downward direction. The diverging portion 44 has a lower outlet end 46 which opens in the flow chamber area adjacent the lower end 22, and which is spaced above the outlet 24. The diverging portion 44 defines a bubble contact chamber 50 within the flow chamber 30. A downflow of liquid conducted through the funnel member 38 experiences a decrease in velocity from a maximum at the inlet portion 40, to a minimum at the outlet end 46 of the diverging portion 44.
The gas dissolution apparatus 10 also includes means for introducing bubbles of gas into the flow chamber 30 for countercurrent movement of the bubbles toward the inlet 20. While various introducing means can be employed, in the illustrated construction the introducing means includes a pair of bubble dispersing units or devices 52 and 54 (see Fig. 2) positioned within the flow chamber 30 proximate the lower end 22 and adjacent the outlet 24. Although the gas dissolution apparatus 10 will function satisfactorily with only a single bubble dispersing device, it is preferred that two or more dispersing devices be used so that shut-off or malfunction of one of the dispersing devices does not prevent operation of the gas dissolution apparatus 10.
As shown in Figure 2, each of the bubble dispersing devices 52 and 54 includes an intermediate gas feed conduit or pipe 56 which is supported on a bracket 58 extending between the inner walls of the outer vessel 14, and which is fitted at one end to the inside end of one of the gas feed pipes 32. Each of the dispersing devices 52 and 54 also includes a bubble diffuser 60 supported on the other end of the feed pipe 56. While gas supplied to the bubble diffusers 60 from the source 34 can be emitted in the form of fine bubbles or course bubbles, it is preferred that fine bubble diffusers be used since fine bubbles expose a larger surface area per bubble volume to contact with the liquid than do larger bubbles. It is preferred that bubbles emitted generally range from 1mm - 3mm in diameter.
While the bubble diffusers could have other constructions, in the illustrated arrangement they are each comprised of fine bubble membrane diffusers of the type used in waste water treatment tanks. Such diffusers are commercially available and are manufactured by Envirex Inc., Waukesha, Wisconsin.
As shown in Figure 3, each fine bubble diffuser 60 includes a disc-like body member 64 having a generally circular membrane supporting or backing surface 66 which has one or more centrally located openings 68. The body member 64 also includes a central gas inlet member 70 defining a passage 72 which communicates between the openings 68 and one of the feed pipes 56. The bubble diffusers 60 can be mounted on the feed pipes 56 via a threaded connection between respective inlet members 70 and feed pipes 56.
The fine bubble diffusers 60 each also include a membrane 74 which is perforated with a large number of relatively small holes or pores. The membrane 74 is attached at its periphery in sealing relationship to the rim of the backing surface 66. The center of the membrane 74 is held to the center of the backing surface 66 by a fastener 76 such as a bolt and nut. When air from the source 34 is delivered through the feed pipes 32 and 56, passage 72, and openings 68, the membrane 74 distends and moves away from the backing surface 66, thereby opening the pores and allowing small bubbles of gas to emanate therefrom. When gas under pressure is no longer provided, the membrane 74 collapses against the backing surface 66 and the pores close.
The fine bubble diffusers 60 are located proximate the lower end 22 and above the outlet 24, and preferably directly below the outlet end 46 of the funnel member 38 for reasons set forth more fully below. The gas bubbles emitted by the fine bubble diffusers 60 have a buoyant velocity greater than the downflow velocity of the water at the outlet end 46, so that the bubbles flow upwardly in the countercurrent direction into the bubble contact chamber 50. Similarly, the air bubbles have a buoyant velocity less than the downflow velocity of the water in the inlet portion 40. Water turbulance in the funnel member 38 generally prevents air bubbles from coalescing to form larger bubbles which may have sufficient buoyant velocity to travel upwardly into the inlet portion 40. Thus, the bubbles will tend to suspend in the contact chamber 50 where the buoyant velocity of the bubbles and the downflow velocity of the water are at equilibrium. This equilibrium area is generally designated by upper and lower bounds shown by dashed lines 78 and 79 in Figure 1.
Although countercurrent contact is expected to increase dissolution of oxygen in the water, air bubbles entrapped in the contact chamber 50 contain some oxygen which will nevertheless remain undissolved. If left in the contact chamber 50 these air bubbles can accumulate until they are crowded out of the outlet end 46, thereafter rising to the collection well 42 for removal from the gas dissolution apparatus 10 as will be further explained below. Since commercial oxygen or the generation of oxygen enriched air can be expensive, recirculation of these gases is desired.
Accordingly, the gas dissolution apparatus 10 includes means for recirculating the air bubbles contained within the contact chamber 50. While various recirculating means can be employed, in the illustrated arrangement the recirculating means includes upper and lower recirculating conduits 80 and 82 communicating between the bubble contact chamber 50 and the inlet 20. While a single recirculating conduit can be used, a pair of conduits 80 and 82 is preferred. The upper and lower recirculating conduits 80 and 82 respectively communicate with the bubble contact chamber 50 at the upper and lower bounds 78 and 79 of the area in which bubbles tend to accumulate in the contact chamber 50. The motive force behind the bubble recirculation is the pressure differential existing between the contact chamber 50 and the inlet 20.
As gas bubbles rise from the fine bubble diffusers 60 other gases, such as nitrogen for example, are stripped from the water by the oxygen in the bubbles. Impurities are thereby removed from the water as the water flows downwardly, while the purity of the oxygen containing gas bubbles is reduced as the bubbles ascend. Thus, locating the fine bubble diffusers 60 proximate the lower end 22 and near the outlet 24 facilitates contacting the water exiting the outlet end 46 of the funnel member 38 with the best quality gas bubbles (i.e. gas bubbles which contain the highest amount of oxygen) prior to leaving the gas dissolution apparatus 10 through the outlet 24. Contacting the water leaving the system with the best quality oxygen tends to increase the amount of oxygen dissolved in the water.
The stripped or waste gases are displaced from the outlet end 46 of the funnel member 38 and are contained within the flow chamber 30, traveling upwardly into the collection well 42. Accordingly, the gas dissolution apparatus 10 includes means for removing contaminents such as these and other waste gases. While various removing means can be employed, in the illustrated construction the removing means includes a gas vent conduit 84 communicating with the collection well 42 for removing waste gases therefrom. The removal means also includes a liquid removal conduit 86 projecting through the upper end 18 of the outer vessel 14. In the event liquid waste other than water collects in the upper end of the flow chamber 30, these waste products can be removed through the liquid removal conduit 86.
The water entering the gas dissolution apparatus 10 can include contaminants such as iron and lead. These impurities combine with the oxygen in the gas bubbles to form precipitates such as oxides of iron and lead. Accordingly, the gas dissolution apparatus 10 includes means for blow-down removal to remove these solids. In the illustrated arrangement the blow-down removal means includes a blow-down removal conduit 88 which is fitted with a valve 90 for controlling blow-down withdrawal.
Illustrated in Figure 4, is a liquid treatment system 92 which incorporates the gas dissolution apparatus 10, and which functions to remove contaminents or impurities from the liquid. While the liquid treatment system 92 can be used for treating a variety of different liquids, in the illustrated arrangement, the system is designed to remove organics such as gasoline constitutents including benzene, toluene, ethylbenzene, and xylene (BTEXs) from groundwater polluted by sources such as leaky underground fuel storage tanks (not shown).
The system 92 includes a reactor 94 which is preferably a fluid bed reactor of the type disclosed in U.S. Patent Nos. 4,009,098 and 4,009,105, each issued on February 22, 1977 to Jeris, and each of which is incorporated herein by reference.
As shown in Figure 8, the reactor 94 is in the form of an upright cylindrical column and includes a water intake manifold 96 at its base. The reactor 94 also preferably includes a biologically active fluid bed having a bed material 98 which comprises granular activated carbon, although other bed materials can also be used. The bed material 98 acts as a substrate for microorganisms which consume the BTEXs and oxygen dissolved in the water.
As shown in Figure 4, the system 92 also includes a water intake pipe 100, and a reactor feed pipe 102 communicating between the outlet pipe 26 of the gas dissolution apparatus 10 and the manifold 96 of the reactor 94.
In operation, contaminated groundwater is fed to the gas dissolution apparatus 10 through water intake pipe 100 with the assistance of a pump 104. The gas dissolution apparatus 10 functions to preoxygenate the water by dissolving oxygen from the source 34 into the groundwater, as previously described. The oxygen enriched groundwater exiting the gas dissolution apparatus 10 is conducted through the reactor feed pipe 102 with the aid of a pump 106, for introduction into the reactor 94 via the manifold 96. The oxygenated groundwater then flows upwardly through the fluid bed so that the bed material 98 is bouyed between upper and lower interfaces, indicated by dashed lines 108 and 110 in Figure 8. The BTEXs and the dissolved oxygen in the upflow are consumed by the microorganisms carried by the bed material 98. BTEXs not immediately consumed by the biological material are adsorbed on the bed material 98 until they can be consumed. Purified groundwater leaves the system 92 through a reactor outlet pipe 112. If amounts of BTEXs remain in the groundwater when it reaches the top of the reactor 94, this partially impure water can be recirculated through the system 92 via a groundwater recirculation pipe 114 which feeds the partially impure groundwater back into the intake pipe 100.
A first alternative embodiment of the gas dissolution apparatus is illustrated in Figure 5. In this embodiment, the means for recirculating does not include recirculation conduits 80 and 82, but instead includes a recirculation conduit 116 communicating between the collection well 42 and the inlet 20, and radially located openings 118 in the downwardly diverging portion 44 of the funnel member 38. Gas bubbles traveling upwardly within the funnel member 38 exit through the openings 118 and continue upwardly into the collection well 42. The air in the collection well is then reintroduced into the water by the recirculation conduit 108.
A second alternative embodiment of the gas dissolution apparatus 10 is illustrated in Figure 6. In this embodiment, the flow confinement member 12 does not include the outer vessel 14. The funnel member 38 defines the entire flow chamber 30 and conducts the downflow of water with a decreasing velocity from a maximum in the area adjacent the upper end of the diverging portion 44, to a minimum at the lower end thereof. The downwardly diverging portion 44 is closed at its lower end and the outlet pipe 26 extends therefrom.
A third alternative embodiment of the gas dissolution apparatus 10 is illustrated in Figure 7. In this embodiment, the flow confinement member 12 comprises only the outer vessel 14, and not the funnel member 38. A flow distributor 120 spans the upper end of the flow chamber 30 to uniformly distribute the incoming water throughout the horizontal cross section of the flow chamber, and to insure that the liquid downflow velocity is not so great as to prevent countercurrent movement of the bubbles.
Various features of the invention are set forth in the following claims.

Claims

An apparatus for dissolving gas in a liquid, said apparatus comprising
a flow confinement member including an inlet, and an outlet, said flow confinement member defining a flow chamber for conducting the liquid between said inlet and said outlet, and
means for introducing bubbles of the gas into said flow chamber for countercurrent movement of the bubbles towards said inlet.
An apparatus as set forth in Claim 1, wherein said means for introducing introduces the bubbles into the flow chamber area adjacent said outlet, and wherein the bubbles entering the liquid are sized to have a buoyant velocity greater than the downflow velocity of the liquid adjacent said outlet.
An apparatus as set forth in Claim 2, wherein said flow confinement member includes an upper end having said inlet, and a lower end having said outlet, and wherein said means for introducing includes a bubble dispersing device positioned within said flow chamber proximate said lower end and above said outlet.
An apparatus as set forth in Claim 3, wherein said flow chamber conducts the liquid between said inlet and said outlet with a decreasing downflow velocity from a maximum downflow velocity in the area adjacent said upper end to a minimum downflow velocity in the area adjacent said lower end.
An apparatus as set forth in Claim 3, wherein said flow confinement member is a vessel, and wherein said apparatus includes a flow distributer positioned within said the flow chamber proximate said upper end, and said means for introducing includes a bubble dispersing device in the flow chamber proximate said lower end and above said outlet.
An apparatus as set forth in Claim 3, wherein the downflow velocity of the liquid in the area adjacent said upper end is greater than the buoyant velocity of the bubbles.
An apparatus as set forth in Claim 6, wherein said flow confinement member includes a funnel member having a downwardly diverging portion which defines a bubble contact chamber between said inlet and said outlet.
An apparatus as set forth in Claim 7, wherein said downwardly diverging portion entraps the bubbles in said contact chamber, and wherein said apparatus includes means for recirculating the entrapped bubbles including a recirculation conduit communicating between said contact chamber and said inlet.
An apparatus as set forth in Claim 1, wherein said flow confinement member comprises an outer vessel including an upper end and a lower end having said outlet, and a funnel member extending downwardly into said flow chamber from said upper end.
An apparatus as set forth in Claim 9, wherein said funnel member includes a downwardly diverging portion defining a bubble contact chamber, and having an outlet end which opens in the flow chamber area adjacent said lower end, and wherein said means for introducing introduces the bubbles into the flow chamber area adjacent said lower end for upward movement of the bubbles into said bubble contact chamber, said bubbles being sized to have a buoyant velocity greater than the downflow velocity of the liquid exiting said outlet end.
An apparatus as set forth in Claim 10, wherein said funnel member includes an inlet portion which extends between said downwardly diverging portion and said upper end, and which defines said inlet, and wherein the downflow velocity of the liquid flowing through said inlet portion is greater than the buoyant velocity of the bubbles.
An apparatus as set forth in Claim 11, wherein said means for introducing includes a bubble dispersing device positioned in the area adjacent said outlet end of said downwardly diverging portion and above said outlet.
An apparatus as set forth in Claim 11, wherein said apparatus includes means for recirculating the bubbles in said contact chamber.
An apparatus as set forth in Claim 13, wherein said means for recirculating includes a recirculation conduit communicating between said contact chamber and said inlet.
An apparatus as set forth in Claim 13, wherein said inlet portion cooperates with said outer vessel to define a gas collection well in the uppermost part of said flow chamber.
An apparatus as set forth in Claim 15, wherein said downwardly diverging portion has therein an opening, and wherein said means for recirculating includes a recirculation conduit communicating between said collection well and said inlet.
An apparatus as set forth in Claim 15, wherein said apparatus comprises means for removing contaminants from said flow chamber, said means for removing including a gas vent conduit communicating with said collection well, a liquid removal conduit extending through said upper end and into said flow chamber, and means for removing blow-down from said flow chamber.
An apparatus for dissolving gas in a liquid, said apparatus comprising
a flow confinement member including an inlet, and an outlet, said flow confinement member defining a flow chamber for conducting the liquid between said inlet and said outlet, and
means for introducing bubbles of the gas into said flow chamber, said means for introducing including a bubble dispersing device positioned in the flow chamber area adjacent said outlet.
An apparatus as set forth in Claim 18, wherein said flow confinement member includes an upper end having said inlet, and a lower end having said outlet, and wherein said bubble dispersing device is positioned proximate said lower end and above said outlet.
An apparatus as set forth in Claim 19, wherein the bubbles introduced into the flow chamber by said bubble dispersing device are sized to have a buoyant velocity greater than the downflow velocity of the liquid in the flow chamber area adjacent said lower end so that the bubbles travel in a countercurrent direction towards said inlet.
An apparatus as set forth in Claim 19, wherein said flow confinement member includes an outer vessel having said upper end and said lower end, and a funnel member including a tubular portion which defines said inlet, and a downwardly diverging portion extending into said flow chamber from said tubular portion, and including an outlet end opening in the flow chamber area adjacent said lower end, and wherein said bubble dispersing device is positioned adjacent said outlet end.
An apparatus for dissolving gas in a liquid, said apparatus comprising
a flow confinement member including an outer vessel which has an outlet, and which defines a flow chamber, and a funnel member having a tubular portion which defines an inlet in said flow confinement member, and a downwardly diverging portion extending into said flow chamber from said tubular portion, and
means for introducing bubbles of the gas into the flow chamber.
An apparatus as set forth in Claim 22, wherein said funnel member conducts a downflow of the liquid into said outer vessel, and wherein said means for introducing introduces the bubble into said downflow.
An apparatus as set forth in Claim 22, wherein said downwardly diverging portion defines a bubble contact chamber, and wherein said bubbles emitted by said means for introducing travel within said bubble contact chamber.
An apparatus for dissolving gas in a downflow of
liquid, said apparatus comprising;
an outer vessel including an upper end having an inlet, and a lower end having an outlet, said outer vessel defining a flow chamber for conducting the downflow between said inlet and said outlet,
a funnel member including a tubular portion which defines at least part of said inlet, and which cooperates with said outer vessel to define a collection well, and a downwardly diverging portion extending downwardly into said flow chamber from said tubular portion, said downwardly diverging portion including an outlet end, and defining a bubble contact chamber, and
means for introducing bubbles of gas into the downflow, said means for introducing including a source of gas under pressure, and a bubble dispersing device connected to said source, and positioned within said flow chamber adjacent said outlet end of said downwardly diverging portion so that the bubbles travel in a countercurrent direction into said bubble contact chamber and toward said inlet, and wherein the bubbles are sized to have a buoyant velocity greater than the downflow velocity of the liquid exiting said outlet end, and wherein the downflow velocity of the liquid in the tubular portion is greater than the buoyant velocity of the bubbles.
An apparatus for removing contaminants from a liquid, said apparatus comprising
a gas dissolution apparatus for dissolving a gas in the liquid, said gas dissolution apparatus including a flow confinement member having an inlet and an outlet, said flow confinement member defining a flow chamber for conducting a downflow of the liquid between said inlet and said outlet, and means for introducing bubbles of gas into said flow chamber,
a source of gas communicating with said means for introducing, and
a reactor communicating with said outlet.
An apparatus as set forth in Claim 26, wherein the gas includes oxygen, and the liquid includes water, and said reactor is a fluid bed reactor which contains a bed material and a biological growth on said bed material for removing the contaminants from the water.
An apparatus as set forth in Claim 27, wherein said flow confinement member includes an upper end having said inlet, and a lower end having said outlet, and wherein said means for introducing includes a bubble dispersing device positioned in said flow chamber proximate said lower end and above said outlet.
An apparatus as set forth in Claim 27, wherein said flow confinement member comprises an outer vessel defining said flow chamber, and a funnel member extending downwardly into said flow chamber from said inlet, said funnel member including a downwardly diverging portion defining a bubble contact chamber, and wherein the bubbles introduced by said means for introducing travel in a countercurrent direction into said contact chamber.